The rate of duping is increasing daily. The few people (or one) that is duping is using the gold they make from their original dupes to buy other better, more godly items and dupe them too. They could dump 100's of Echoing Fury's in the AH right now, but are smart and realize if they release too much at one time the economy will collapse immediately. By releasing items at a slow rate, they maximize their profit.
In the mean time, the economy will crash. Any items below the dupes will grow to be worthless. Farming will be a waste of time as duped godly items will be prevalent, and most people will have the same gear.
It's a runaway train guys. I'm sure Bliz is aware of it, but is currently unable to find the duping method right now to patch it. Bliz has a few weeks to a month to figure out the problem and stop it, but otherwise it's game over. D3 will turn into D2, where only godly items were traded.
I've heard people say, "It's no big deal, the duping isn't that prevalent, there are only a few duped items" No. You are wrong. The duping is infinite if the dupers wanted it to be. They are merely choosing to not flood the AH with them at one time to maximize their profit. It's economy 101.
It's sad, but true.